Merge pull request #1034 from lilleswing/fix-merge

      d = json.load(fin)

      return NumpyDataset(d['X'], d['y'], d['w'], d['ids'])

  @staticmethod

  def merge(datasets):

    """

    Parameters

    ----------

    datasets: list of deepchem.data.NumpyDataset

      list of datasets to merge

    Returns

    -------

    Single deepchem.data.NumpyDataset with data concatenated over axis 0

    """

    X, y, w, ids = datasets[0].X, datasets[0].y, datasets[0].w, datasets[0].ids

    for dataset in datasets[1:]:

      X = np.concatenate([X, dataset.X], axis=0)

      y = np.concatenate([y, dataset.y], axis=0)

      w = np.concatenate([w, dataset.w], axis=0)

      ids = np.concatenate(

          [ids, dataset.ids],

          axis=0,

      )

    return NumpyDataset(X, y, w, ids, n_tasks=y.shape[1])

class DiskDataset(Dataset):

  """

    assert len(valid_data) == 1

    assert len(test_data) == 1

    merged_dataset = dc.data.DiskDataset.merge(

    merged_dataset = dc.data.NumpyDataset.merge(

        [train_data, valid_data, test_data])

    assert sorted(merged_dataset.ids) == (sorted(solubility_dataset.ids))